High-gain antenna reflectors have been deployed into space from launch vehicles for several decades. The configurations of such reflectors have varied widely as material science developed and as the sophistication of technology and scientific needs increased.
Large diameter antenna reflectors pose particular problems both during deployment and post-deployment. Doubly-curved, rigid surfaces which are sturdy when in a deployed position cannot be folded for storage. Often, reflectors are stored one to two years in a folded, stored position prior to deployment. In an attempt to meet this imposed combination of parameters, large reflectors have been segmented into petals so that these petals could be stowed in various overlapped configurations. However, the structure required in deploying such petals has tended to be rather complex and massive, thus reducing the feasibility of such structures. For this reason, parabolic antenna reflecting surfaces larger than those that can be designed with petals typically employ some form of a compliant structure. Reference is made to U.S. Pat. No. 4,899,167, for its disclosure of such a system.
Responsive to the need for such a compliant structure, rib and mesh designs have been built, tested and used. However, such antenna tend to suffer from chording in both radial and circumferential directions. The use of mesh in such a configuration has an inherent disadvantage in diminishing the reflective quality of the resulting parabolic surface. Further, a mesh cannot be made to assume a truly parabolic configuration. Reference is made to U.S. Pat. No. 3,707,720 for its disclosure of such a system.
Other antenna designs typically include a center post about which the petals are configured, much like an umbrella configuration. This also affects the reflective quality of the resulting surface, since the center portion typically is the point of optimum reflectance, which is then blocked by the center post. Thus, it is desirable to have a structure that is deployable from a compact, stored position to a parabolic, open position without the use of a center post. Reference is made to U.S. Pat. Nos. 3,286,270; 3,397,399 and 3,715,760 which disclose such systems.
More recently, rigid antenna reflectors have been constructed from carbon fiber-reinforced plastic materials (CFRP). Such material can satisfy the requirements for space technology, contour accuracy and high performance antenna systems. However, performance of such antenna has been limited, owing to the size of the payload space in a carrier space vehicle. Very large completely rigid antenna are highly impractical to launch into space, hence until the present, requirements for practical purposes could be satisfied only when the antenna was of a collapsible and foldable construction. Reference is made to U.S. Pat. Nos. 4,092,453 and 4,635,071 which disclose such fabrics.
Large lightweight flexible antennas have been formed from graphite fiber-reinforced plastic composite fabrics which can be wrapped into compact form, launched and caused to unfold to provide large L-band-reflective antennas. Such reflectors do not have a fixed reflector surface accuracy and therefore do not have Ku-band reflective properties.
Thus, there remains a need for a large, compactable, lightweight, deployable antenna assembly having a reflector surface area having a high reflector surface accuracy suitable for Ku-band radiation, and which is capable of storage within and deployment from the payload space of a carrier space vehicle, while being free of the aforementioned disadvantages.